Measuring instrument, optical reader and optically-readable measure

ABSTRACT

A measuring instrument includes: a measure on which a code having color patterns is printed; a plurality of first readers that optically read colors of first ranges in first patterns corresponding to digits except a least significant digit among the color patterns, the first ranges in the first patterns being arranged in a second direction; and a plurality of second readers that optically read colors of second ranges in second patterns arranged in a first direction corresponding to patterns of the least significant digit among the color patterns, the second ranges being arranged in the first direction at an interval different from a width of the pattern in the first direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is Divisional Application of U.S. application Ser. No.16/414,108 filed on May 16, 2019 which claims the benefit of priority ofthe prior Japanese Patent Application No. 2018-106211 filed on Jun. 1,2018, the entire contents of each of which are incorporated herein byreference.

FIELD

A certain aspect of the embodiments is related to a measuringinstrument, an optical reader, and an optically-readable measure.

BACKGROUND

When cloths are made or resized in a clothing store, a clerk generallymeasures dimensions of the cloths using a measure. The clerk enters themeasurement data in a dimension sheet of each customer by hand, and thenmanually inputs the measurement data to a terminal of the store. In thiscase, the work for entering the measurement data in the dimension sheetand the work for inputting the measurement data to the terminal arerequired, and therefore double labors occur.

In order to solve this problem, there has been known an apparatus whichcan input the measurement data to the terminal without using thedimension sheet (e.g. see Patent Document 1: Japanese Laid-open PatentPublication No. 7-35535). The apparatus includes: a transmitter that hasa measure measuring the dimensions of a measurement object, andtransmits the measurement data; and a measure signal receiver andrecorder that receives a signal including the measurement datatransmitted from the transmitter and prints the measurement data. In thetransmitter, a binary code comprised of white dots and black dotsprinted on the measure is read optically by a reader, the read data isdecoded, and the decoded data is transmitted to the receiver andrecorder.

Similarly, there have been known a length measuring instrument and aposition measuring instrument that optically read patterns such asbinary digital codes (e.g. see Patent Document 2: Japanese Laid-openPatent Publication No. 2009-75013, and Patent Document 3: JapaneseLaid-open Patent Publication No. 5-272916).

SUMMARY

According to an aspect of the present invention, there is provided ameasuring instrument including: a measure on which a code having aplurality of color patterns is printed, each of the color patternshaving a plurality of digits to which values of a N-ary number areassigned (N is 3 or more), one of different colors respectivelycorresponding to one of N-ary values being assigned to each patterncorresponding to each digit included in each color pattern, the patterncorresponding to each digit being arranged in a second directionintersecting a first direction, a humming distance between adjacentcolor patterns in the first direction being 1, and an amount of changein the value at one of the digits included in the adjacent colorpatterns being 1; a plurality of first readers that optically readcolors of first ranges in a plurality of first patterns corresponding todigits except a least significant digit among the color patterns,respectively, the first ranges in the first patterns being arranged inthe second direction; and a plurality of second readers that opticallyread colors of second ranges in a plurality of second patterns arrangedin the first direction corresponding to patterns of the leastsignificant digit among the color patterns, respectively, the secondranges being arranged in the first direction at an interval differentfrom a width of the pattern in the first direction.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the configuration of a length measuringinstrument according to a present embodiment;

FIG. 2 is a diagram illustrating a reading processing of a color patternof a ternary number;

FIG. 3A is a diagram illustrating an example of the color pattern of theternary number;

FIG. 3B is a diagram illustrating an example of a color pattern by aternary Gray code;

FIG. 4 is a diagram illustrating a reading processing of the colorpattern by the ternary Gray code;

FIG. 5 is a diagram illustrating an example of a color pattern of a codethat has improved the ternary Gray code using three colors;

FIG. 6 is a diagram illustrating a method of creating a new ternary Graycode in which binary change does not occur from the ternary Gray code;

FIG. 7 is a flowchart illustrating a processing operation of themeasuring instrument;

FIG. 8 is a diagram illustrating a reader unit of the measuringinstrument according to a first embodiment;

FIG. 9A is an enlarged view of the color pattern according to the firstembodiment;

FIG. 9B is an enlarged view of a single pattern;

FIG. 10 is an enlarged view of the color pattern according to the firstembodiment;

FIG. 11 is an enlarged view of the color pattern according to the firstembodiment;

FIG. 12 is an enlarged view of the color pattern according to the firstembodiment;

FIG. 13 is a diagram illustrating a table used in the first embodiment;

FIG. 14 is a flowchart illustrating a processing executed by amicrocomputer according to a first variation of the first embodiment;

FIG. 15 is a diagram illustrating a table used in the first variation ofthe first embodiment;

FIG. 16A is an enlarged view of a color pattern according to a secondvariation of the first embodiment;

FIG. 16B is an enlarged view of the pattern;

FIG. 17 is an enlarged view of the color pattern according to the secondvariation of the first embodiment; and

FIG. 18 is an enlarged view of the color pattern according to the secondvariation of the first embodiment.

DESCRIPTION OF EMBODIMENTS

In the above-mentioned conventional measuring instrument, it is requiredto suppress increase in size and improve a reading accuracy.

Hereinafter, a description will be given of the present embodiment ofthe present invention with reference to the drawings.

FIG. 1 is a diagram illustrating the configuration of a length measuringinstrument according to a present embodiment. In one example, the lengthmeasuring instrument may be used in a clothing store, but may be usedfor any other purposes.

A length measuring instrument (hereinafter referred to as “a measuringinstrument”) 1 includes: a reader unit 2 that reads a color pattern froma measure 7 a having multi-digit color patterns; a microcomputer 3 as ameasuring means that calculates a length of a measurement object fromdata read by the reader unit 2; a communication device 4 that transmitsdata of the calculated length of the measurement object to an externalterminal 10 by wired or wireless communication; a switch 5 thatinstructs the start of the measurement to the microcomputer 3; a battery6 that supplies an electric power to the reader unit 2, themicrocomputer 3 and the communication device 4; and a storage 7 thatstores the measure 7 a,

The measuring instrument 1 and the external terminal 10, or themeasuring instrument 1 alone, may configure a measuring system formeasuring and determining a length of a measurement subject. In thelatter case, the measuring instrument 1 may perform functions of theexternal terminal 10 that are described herein. The measuring system mayfurther include other devices such as a server, a storage device, or anytype of communication devices. The measuring system may have functionsfor storing measured lengths, or processing the measured lengths forcertain purposes such as making clothes for example. These functions arerealized by executing software in the external terminal 10 or otherdevices.

The reader unit 2 includes: light emitting diodes (LEDs) 8 each of whichirradiates the color pattern with a light; and phototransistors (PTs) 9each of which receives a reflection light from the color pattern, andconverts it into a current or voltage with a value corresponding to areceiving light amount. The LED 8 is irradiated with light, includinginfrared, a visible light and an ultraviolet light. The PT 9 receivesthe light reflected by the color pattern. A set of the LED 8 and the PT9 corresponds to the reader unit described later. The LED 8 is used as alight emitting element, and the PT 9 is used as a light receivingelement. However, a light emitting element other than the LED 8 may beused, and a light receiving element other than the PT 9 may be used.

The microcomputer 3 is a processor such as a central processing unit(CPU). The microcomputer 3 controls on/off of the LED 8, and reads thecurrent value or voltage value of the output from the PT 9. Since thereflectivities are different by the colors of the color patterns, andthe light receiving amount of the PT 9 varies depending on thereflectivities, the microcomputer 3 is capable of determining the colorby the current value or voltage value output from the PT 9. When thevoltage values output from the PT 9 are 2.0V, 1.5V and 1.0V, forexample, the microcomputer 3 determines that the colors of the colorpattern are white, blue and black, respectively.

A scale is printed on a front surface of the measure 7 a along alongitudinal direction as similar to a conventional measure, and thecolor pattern of the base N number Gray code (N-ary Gray code) using Ncolors (N>=3) is printed on a back surface of the measure 7 a for eachconstant length, for example. The base N number Gray code is describedlater. Also, instead of using N different colors in each digit of thecolor pattern, the same color with N different concentrations may beused, for example. Here, the differences in such concentrations of thecolor pattern are also treated as “different colors”. The storage 7 isremovably attached to a housing of the measuring instrument 1. In FIG. 1, the measure 7 a is housed in the storage 7. However, a measure may notbe stored in storage or in a measuring instrument, as long as themeasuring instrument can read color patterns on the measure. Forinstance, a measuring instrument may have a slit for slidably passing ameasure.

The external terminal 10 is a terminal device such as a computer orsmart phone having a wired or wireless communication function, receivesthe data of the length of the measurement object from the communicationdevice 4, and registers and manages the data in the database. Thedatabase for registering the data of the length may be incorporated inthe external terminal 10, or may be provided outside of the externalterminal 10 in an accessible state. Further, softwares for processingthe measured length may be stored in the external terminal 10 or in anyother device in which the external terminal 10 is accessible.

FIG. 2 is a diagram illustrating a reading processing of a color patternof a ternary number,

In the example of FIG. 2 , a color pattern 11 of the ternary number iscomposed of 6 digits, and three colors of white, blue and black areadopted as colors corresponding to ternary values “0”, “1” and “2”,respectively. The reflectivity is high in order of white, blue andblack. Each line of the ternary color pattern 11 corresponds to certaindecimal number as illustrated in FIG. 2 , and each decimal numbercorresponds to a certain length. In FIG. 2 , the decimal numbers arearranged in an ascending order, but the decimal numbers may be arrangedin a descending order, for example. In FIG. 2 , a value and a digitnumber of the ternary number corresponding to each color are describedfor convenience of explanation, but it is not necessary to show thevalue and the digit number of the ternary number in the actual colorpattern or on the measure 7 a. A voltage value output from the PT 9 isanalog data. It is assumed that, when white, blue and black are read,voltage values output from the PT 9 are 2.0V, 1.5V and 1.0V,respectively.

A single set of the LED 8 and the PT 9 is assigned so as to read asingle digit pattern of the color pattern 11. To read a measure with thesix-digit color patterns illustrated in FIG. 2 , at least six sets ofthe LED 8 and the PT 9 are provided in the measuring instruments 1.

When a region 21 of the color pattern 11 is read, each of the PTs 9corresponding to white digit numbers 1 to 3 outputs 2.0V, each of thePTs 9 corresponding to blue digit numbers 4 and 6 outputs 1.5V, and thePT 9 corresponding to black digit number 5 outputs 1.0V. Themicrocomputer 3 determines the color of each digit based on the voltagevalue output from each of the PT 9, and converts the color into acorresponding ternary value. In an example of FIG. 2 , the pattern inthe region 21 is converted into a ternary value “000121”. Themicrocomputer 3 calculates a length of a measurement object byconverting the ternary value “000121” into a decimal value. In theregion 21, the ternary value “000121” is converted into a decimal value“16”, and may be further converted into a certain length corresponds tothe decimal number “16”. The read ternary value may be directlyconverted into a certain length data without converting into a decimalvalue. In FIG. 2 , the value calculated from the reading result of theregion 21 is identical with the value assigned to the region 21.

On the other hand, in the region 22, the color pattern 11 is read acrosstwo adjacent lines, i.e., a line corresponds to a decimal number “8” anda line corresponds to a decimal number “9”. When the region 22 is read,each of the PTs 9 corresponding to the digit numbers 1 to 3 in whichboth lines are white outputs 2.0V. However, the PT 9 corresponding tothe digit number 4 in which one line is white and the other line is bluemay output 1.75V, that is in the middle of 2.0V and 1.5V, and each ofthe PTs 9 corresponding to the digit numbers 5 and 6 in which one lineis white and the other line is black may output 1.5V, that is in themiddle of 2.0V and 1.0V, for example. As a voltage value output fromeach of the PTs 9 is the analog data, an intermediate value of colors ofadjacent upper and lower patterns is output from the PT 9 when each PT 9is located at the boundary of two lines in the color pattern 11 andreads the color patterns of the two lines.

When the region 22 is read, the voltage values of “2.0V, 2.0V, 2.0V,1.75V, 1.5V, 1.5V” corresponding to the digit numbers 1 to 6 are outputfrom the PTs 9 in the described example. Since each of the outputvoltage values of the digit numbers 5 and 6 corresponds to a voltagevalue when the blue color pattern is read, the microcomputer 3recognizes that the color pattern corresponding to the value “1” hasbeen read for the digit numbers 5 and 6. On the other hand, since theoutput voltage value of the digit number 4 is just the middle ofvoltages 2.0V corresponding to the white color pattern and 1.5Vcorresponding to the blue color pattern, the microcomputer 3 cannotdetermine whether either value “0” or “1” has been read.

Therefore, the microcomputer 3 may convert the read pattern of theregion 22 into either the ternary value “000011” or “000111” based onthe voltage value from each PT9, and converts the ternary value into adecimal value to calculate the length of the measurement object.However, the ternary value “000011” or “000111” is not identical withboth of the values “000022” and “000100” located in the region 22.Moreover, the decimal value “4” or “13” corresponding to the ternaryvalue “000011” or “000111”is not the same as the decimal value “8” or“9” corresponding to two lines of region 22. For this reason, themeasured length calculated by the microcomputer 3 is not identical withthe actual length of the measurement object, and an error occurs in thereading. Thus, when the color pattern 11 of FIG. 2 is adopted, a readingerror may occur at the boundary of the color pattern 11.

FIG. 3A is a diagram illustrating an example of the color pattern of theternary number explained in FIG. 2 . FIG. 3B is a diagram illustratingan example of another color pattern 12 by a ternary Gray code.

Since the intermediate value of the upper and lower patterns is obtainedif the boundary of the adjacent color patterns is read as describedabove, when the color pattern 11 as illustrated in FIG. 3A is used,there is a case where an error occurs between the actual length of themeasurement object and the measured length calculated by themicrocomputer 3.

One of the reasons for such error occurrence is that the color change,in which a change of the colors between the adjacent upper and lowercolor patterns, occurs in a plurality of digits, as indicated in theregions 23 to 25 of FIG. 3A. For example, in the regions 23 and 24, thecolor change occurs in two digits, the digit numbers 5 and 6. In theregion 25, the color change occurs in three digits, the digit numbers 4to 6.

To solve the error occurrence of the measurement value, it isconceivable to adopt the color pattern 12 by the ternary Gray code asillustrated in FIG. 3B. In the color pattern 12 by the ternary Graycode, the color change in the adjacent upper and lower color patternsoccurs in only one digit.

FIG. 4 is a diagram illustrating a reading processing of the colorpattern 12 by the ternary Gray code.

When a region 27 of the color pattern 12 is read, each of the PTs 9corresponding to white digit numbers 1 to 3 outputs 2.0V, each of thePTs 9 corresponding to blue digit numbers 4 and 6 outputs 1.5V, and thePT 9 corresponding to black digit number 5 outputs 1.0V. Themicrocomputer 3 determines the color of each digit based on the voltagevalue from each PT 9, and converts the read color into the correspondingternary valueGray. From a pattern of the region 27 of FIG. 4 , a ternaryvalue Gray“000121” is obtained. The microcomputer 3 converts the ternaryvalue Gray“000121” into a decimal value to calculate the length of themeasurement object. Here, well-known methods are used as a method ofconverting Graythe ternary number into the decimal number. In the region27, the ternary valueGray “000121” is converted into a decimal number“10”, by referring to a table showing a relationship between the ternarynumber and the decimal number, for instance. Since the region 27corresponds to the decimal number “10”, the length of the measurementobject is identical with the length indicated by the measure 7 a.

On the other hand, when a region 28 of the color pattern 12 is read,each of the PTs 9 corresponding to the digit numbers 1 to 4 in whichupper and lower patterns are white outputs 2.0V, and the PT 9corresponding to the digit number 5 in which the upper and lowerpatterns are blue outputs 1.5V. On the contrary, the PT 9 correspondingto the digit number 6 in which one line is black and the other line iswhite may output 1.5V. The microcomputer 3 may determine that theternary Gray code corresponding to the region 28 is “000011” based onthe output voltage value from the PTs 9. The microcomputer 3 convertsthe ternary value “000011” into a decimal value “5” to calculate thelength of the measurement object. Although an error is smaller than theerror of the example of FIG. 2 , the color patterns “000012” and“000010” located in the region 28 correspond to decimal values “3” and“4”, and therefore they are not identical with the decimal number “5”calculated by the microcomputer 3.

The reason why the error occurs even when the color pattern 12 by theternary Graycode illustrated in FIG. 4 is used is that a binary changeoccurs in the digits of the upper and lower patterns adjacent to theboundary of the color pattern 12. The binary change means that adifference between values of the same digit of the upper and lowerpatterns is 2 or more, i.e., means that there is a change of white andblack in the color pattern 12 of FIG. 4 .

In the digit number 6 of the region 28, the upper pattern adjacent tothe boundary is black (2), and the lower pattern adjacent to theboundary is white (0). In this case, the PT 9 corresponding to the digitnumber 6 may output 1.5V, which is the same as an output voltage valueof the PT 9 when the blue pattern is read, and therefore themicrocomputer 3 determines the color of the digit number 6 as the blue.For this reason, an error may occur between the length of an actualmeasurement object and the measured length calculated by themicrocomputer 3.

When the value change between the upper and lower patterns adjacent tothe boundary of the color pattern 12 is a single value change, such anerror does not occur. The single value change means that the differencebetween values of the same digit of the upper and lower patterns is 1,or that there is a change of white and blue or a change of blue andblack in the color pattern 12 of FIG. 4 .

FIG. 5 is a diagram illustrating another example of a color pattern 13by the ternary Gray code using three colors. The color pattern 13 ofFIG. 5 is capable of improving a problem caused by the color pattern 12.It is assumed that a lateral direction (i.e., a digit direction) of FIG.5 is an X direction, and a vertical direction of FIG. 5 in whichpatterns of the same digit are arranged is a Y direction.

In the color pattern 13, the color change or value change between theadjacent upper and lower patterns occurs in only one digit, and thevalue change is the single value change. Therefore, the ternary Graycode of the color pattern 13 does not cause the binary change. That isto say, in the color pattern 13, a plurality of patterns assigned torespective different decimal values are arranged, each pattern has aplurality of digits to which values of N-ary number are assigned (N is 3or more), and each digit has a different color depending on the assignedvalue. In the example of the color pattern 13, a plurality of patternsare arranged in an ascending or descending order, a humming distancebetween adjacent patterns in the arrangement direction is 1, an amountof change in the value at one of the digits included in the adjacentpatterns is 1, and an amount of change in the value at the other digitsof the adjacent color patterns is 0.

Even when the boundary of the adjacent upper and lower patterns is readand an intermediate value between the voltage values of the upper andlower patterns is output from the PTs 9, the microcomputer 3 can convertthe intermediate value into the decimal value corresponding to eitherone of the upper pattern or the lower pattern by using the color pattern13. For this reason, a substantial error does not occur between thelength of the actual measurement object and the measured lengthcalculated by the microcomputer 3.

Note that the ternary color patterns illustrated in FIG. 4 and FIG. 5are not arranged in an ascending or descending ternary order. Further,the decimal values are not mathematically assigned to each of theternary color patterns. For instance, the ternary value “000121” in theregion 27 of FIG. 4 shall mathematically mean the decimal value “16”,but is actually assigned to the decimal value “10”. In FIGS. 4 and 5 ,decimal values are just assigned to each of the ternary color patternsin the order in which the color patterns are aligned.

FIG. 6 is a diagram illustrating a method of creating a new ternary Graycode in which the binary change does not occur from the ternary Graycode.

A conversion rule to create the new binary Gray code in which the binarychange does not occur from the binary Gray code is as follows:

(1) When the total of the values of the digits upper than a digit to beconverted is 0 or even, the value of the digit to be converted ismaintained;

(2) When the total of the values of the digits upper than the digit tobe converted is odd, and the value of the digit to be converted is 1,the value of the digit to be converted is maintained;

(3) When the total of the values of the digits upper than the digit tobe converted is odd, and the value of the digit to be converted is 2,the value of the digit to be converted is converted into 0; and

(4) When the total of the values of the digits upper than the digit tobe converted is odd, and the value of the digit to be converted is 0,the value of the digit to be converted is converted into 2.

Here, it is assumed that the digit number 1 is the most significantdigit and the digit number 6 is the least significant digit. Moreover,although a digit of the digit number 0 is illustrated in the ternaryGray code of FIG. 6 before conversion, this digit number 0 is animaginary digit that is set for a value conversion processing of thedigit number 1 for convenience and does not exist in the color pattern13. Further, a value “0” as a fixed value is virtually set to a digit ofthe digit number 0.

As an example, a description will be given of a method of creating a newternary Gray code in which the binary change does not occur from theternary Gray code “001010” illustrated in FIG. 6 .

First, a value “0” of the digit number 6 before conversion is converted.Since the total of the values of the digit numbers 0 to 5 upper than thedigit number 6 is 2 (even), the value of the digit number 6 ismaintained to “0” according to the conversion rule (1). Next, the totalof the values of the digit numbers 0 to 4 upper than the digit number 5is 1 (odd), and the value of the digit number 5 is 1. Therefore, thevalue of the digit number 5 is maintained to “1” according to theconversion rule (2).

In the digit number 4, the total of the values of the digit numbers 0 to3 upper than the digit number 4 before conversion is 1 (odd), and thevalue of the digit number 4 is 0. Therefore, the value of the digitnumber 4 is converted from “0” to “2” according to the conversion rule(4). In the digit number 3, the total of the values of the digit numbers0 to 2 upper than the digit number 3 before conversion is 0, andtherefore the value of the digit number 3 is maintained to “1” accordingto the conversion rule (1).

In the digit number 2, the total of the values of the digit numbers 0and 1 upper than the digit number 2 before conversion is 0, andtherefore the value of the digit number 2 is maintained to “0” accordingto the conversion rule (1). Finally, since the value of the digit number0 upper than the digit number 1 before the conversion is 0, the value ofthe digit number 1 is maintained to “0” according to the conversion rule(1).

By such a procedure, the ternary Gray code “001010” is converted intothe new ternary Gray code “001210” in which the binary change does notoccur.

It is also possible to inversely convert from the new ternary Gray codein which the binary change does not occur into the original ternary Graycode in accordance with the conversion rules (1) to (4).

Thus, by determining the conversion rules corresponding to the N-aryGray code, it is possible to create a new N-ary Gray code in which thebinary change does not occur from the N-ary Gray code. When softwareequipped with an algorithm for executing the method of FIG. 6 isoperated on a computer, the new ternary Gray code can be created.

FIG. 7 is a flowchart illustrating a processing operation of themeasuring instrument 1.

First, when the switch 5 is depressed to measure a length of a measuringobject, the start of the measurement is instructed to the microcomputer3 (S1). The microcomputer 3 turns on each LED 8 (S2), and the LED 8irradiates the color pattern 13 with light (S3). Each PT 9 receivesreflected light from the color pattern 13, and outputs a current orvoltage corresponding to the light receiving amount (S4). Themicrocomputer 3 reads a current value or voltage value output from eachPT 9 (S5).

The microcomputer 3 determines a read color of each digit of the colorpattern 13 based on the current value or voltage value outputted fromeach PT 9, calculates an N-ary value of each digit of the N-ary Graycode from the read color of the color pattern 13 Gray, and converts theN-ary value into a decimal value (S6). When calculating the decimalvalue assigned to the color pattern 13 from the ternary value, theternary value obtained by reading the N-ary Gray code is inverselyconverted with the conversion rules as described in connection with FIG.6 , and then the inversely converted ternary value is converted into adecimal value based on a well-known conversion method. The microcomputer3 may be provided beforehand with a table indicating a correspondingrelationship between the colors of each line of the color pattern 13 andthe decimal value, and may determine the decimal value corresponds tothe read ternary number by referring to this table. The table maycontain any other information that can be used to convert the readternary values into decimal values. Then, the microcomputer 3 transmitsdata converted into the decimal number to the external terminal 10 viathe communication device 4 (S7), and terminates the present processing.The external terminal, or other device that is communicatable with theexternal terminal, converts the received decimal number into actualmeasured length.

Since the color pattern is N-ary numbers (N is 3 or more), it ispossible to reduce the number of digits constituting the color patternand thin the width of the measure 7 a, as compared with the case wherethe binary code is printed on the measure. Also, it is possible toreduce the number of reading sensors, i.e., the number of LEDs 8 and PTs9, for reading the color pattern. Therefore, it is possible to reducethe size of the reader unit and the measuring instrument.

When the color pattern 13 as shown in FIG. 5 is used, a measurementaccuracy of the length of the measurement object, in other words aminimum measurable length, depends on a width of each color pattern inthe Y direction. To increase the measurement accuracy, in other word toshorten the minimum measurable length, it is conceivable to narrow thewidth of the color pattern in the Y direction. However, to measure thesame length with such measure, the number of digits in each line of thecolor pattern 13 needs to be increased. In order to increase the numberof digits without changing the width of the measure 7 a, the width ofeach digit of the color pattern in the X direction is required to benarrowed, and therefore the widths in the X direction and the Ydirection of one color pattern need to be reduced. On the other hand, aphoto sensor of the PT 9 has a constant detection range, and a photosensor having a narrow detection range capable of reading narrower colorpatters is expensive. Sometimes it is difficult to narrow an interval inthe X direction between the adjacent photo sensors, and it may bedifficult to read narrower color patterns. As described above, it isdifficult to increase the number of digits in the color pattern.

Hereinafter, a description will be given of an embodiment to improve theaccuracy of the measurement without increasing the number of digits ofthe color pattern 13.

First Embodiment

FIG. 8 is a diagram illustrating the reader unit of the measuringinstrument 1 according to a first embodiment. The reader unit 2 includesfive readers (first readers) 20 arranged in X direction, three readers(second readers) 22 a to 22 c arranged in Y direction, and two readers(third readers) 24 a and 24 c arranged in Y direction. Each of thereaders 20, 22 a to 22 c, 24 a and 24 c includes the LED 8 and the PT 9.

FIG. 9A is an enlarged view of the color pattern according to the firstembodiment. FIG. 9B is an enlarged view of a single pattern. FIG. 9Aillustrates an enlarged range A in FIG. 5 , and illustrates the ternaryvalue in an upper left of each pattern 40. The ternary value does nothave to be shown in the measure 7 a. The values “0”, “1” and “2”correspond to white, blue and black, respectively.

In the color pattern 13, a plurality of patterns 40 are arranged in theX direction and the Y direction, as illustrated in FIG. 9A. The patterns40 of the digit numbers 1 to 6 are denoted as patterns 41 to 46,respectively The patterns 46 of the least significant digit are denotedas the patterns 46 a to 46 g from the upside along the Y direction. Thewidth in the Y direction of each pattern 40 is P1, for example 3 mm. Thewidths P1 of all patterns 40 are substantially the same as each other,and fall within an error range of about a manufacturing error. Each ofthe six patterns 41 to 46 arranged in the X direction corresponds to asingle line of a color pattern. Five ranges 30 and a range 32 bcorrespond to ranges in which each of the readers 20 and the reader 22 bread the patterns 40, respectively. The ranges 30 and 32 b are arrangedin, and are located on a line extending in the X direction. A positionof the line on which the ranges 30 and 32 b are arranged is referred toas a measurement position 36. In FIG. 9A, the measurement position 36 islocated in the center of the pattern 40 in the Y direction, and is areference position of the color pattern reading. In the example of FIG.9A, the accuracy of the length measurement which corresponds to aminimum measurable length is P1, that is 3 mm. Hereinafter, adescription will be given of a method of setting the accuracy of thelength measurement to 1 mm, i.e., one third of the width P1 by using thesame color pattern as FIG. 9A.

The pattern 46 of the least significant digit is virtually divided intothree regions 47 a to 47 c along the Y direction for the purpose of adescription. The regions 47 a to 47 c cannot be visibly distinguishedfrom each other on the measure 7 a. A width in the Y direction of eachof the regions 47 a to 47 c is P3. The P3 is one third of the P1, forexample 1 mm. The widths P3 of the regions 47 a to 47 c aresubstantially the same as each other.

FIGS. 10 to 12 are enlarged views of the color pattern and a readingstate according to the first embodiment. In the example of FIG. 10 , therange 32 b to be read by the reader 22 b is located in the region 47 bof the pattern 46 c, the range 32 a to be read by the reader 22 a islocated in the region 47 a of the pattern 46 b, and the range 32 c to beread by the reader 22 c is located in the region 47 c of the pattern 46d. A distance between the centers of the ranges 32 a and 32 b, adistance between the readers 22 a and 22 b is P2, and a distance betweenthe centers of the ranges 32 b and 32 c, i.e., a distance between thereaders 22 b and 22 c is P2. The distance P2 is a sum of the width P1and the width P3, for example 4 mm.

In FIG. 10 , the colors to be read in the ranges 32 a, 32 b and 32 c areblue (1), white (0) and white (0), respectively. In this case, themicrocomputer 3 determines that the measurement position 36 is locatedin the center of the pattern 46 c in the Y direction which is the centerof the region 47 b in the pattern 46 c.

On the other hand, in the example of FIG. 11 , the range 32 b is locatedin the region 47 c of the pattern 46 c, the range 32 a is located in theregion 47 b of the pattern 46 b, and the range 32 c is located in theregion 47 a of the pattern 46 e. In FIG. 11 , the positions of allreaders are shifted by the width P3 in a −Y direction from theirpositions of FIG. 10 , and the colors to be read in the ranges 32 a, 32b and 32 c are blue (1), white (0) and blue (1), respectively. In thiscase, the microcomputer 3 determines that the measurement position 36 islocated away from the center of the pattern 46 c in the Y direction by adistance +P3.

Similarly, although the illustration is omitted, when the range 32 b islocated in the region 47 a of the pattern 46 c, the range 32 a islocated in the region 47 c of the pattern 46 a, and the range 32 c islocated in the region 47 b of the pattern 46 d. In this state, thepositions of all readers are shifted by the width P3 in a +Y directionfrom their positions of FIG. 10 . The colors to be read in the ranges 32a, 32 b and 32 c of the digit number 6 are black (2), white (0) and blue(1), respectively. In this case, the microcomputer 3 determines that themeasurement position 36 is located away from the center of the pattern46 c in the Y direction by a distance −P3.

In a state of FIG. 10 , in a state of FIG. 11 , and in a state where therange 32 b is located in the region 47 a of the pattern 46 c, the reader22 b which is disposed in the measurement position 36 reads white of thepattern 46 c. On the other hand, in the above-mentioned three states,the reader 22 a reads blue, blue and black, respectively, and the reader22 c reads white, blue and white, respectively. Therefore, it ispossible to determine a positional relationship between the colorpattern and the readers 22 a, 22 b and 22 c from the combination of thecolors which the three readers 22 a, 22 b and 22 c read. In theabove-mentioned three states, each reader is shifted in the Y directionby the distance ±P3. Therefore, by determining the above-mentioned threestates, it is possible to set the measurement accuracy of the length tothe width P3, i.e., 1 mm. In this way, a change in the colors read bythe readers 22 a and 22 c is detected by using the readers 22 a and 22 cdisposed away from the reader 22 b in the Y direction by the distanceP2, which makes it possible to set the measurement accuracy of thelength that corresponds to a minimum measurable length to the width P3which is one third of the width P1.

In the color pattern of FIG. 5 , there is a case where the color of thepattern 46 of the least significant digit is continuous twice in the Ydirection, and therefore, when using three readers 22 a to 22 c, theremay be a case where it cannot be determined that the range 32 b islocated in which of the region 47 a, 47 b or 47 c. Hereinafter, adescription will be given of how to solve this problem with referring toFIG. 12 .

For example, when the measurement position 36 is located in the region47 b of the pattern 46 e as illustrated in FIG. 12 , the patterns 46 d,46 e and 46 f are read in the ranges 32 a, 32 b and 32 c, and the readcolors are white (0), blue (1) and black (2), respectively. On the otherhand, when the measurement position 36 is located in the region 47 a ofthe pattern 46 e, the patterns 46 c, 46 e and 46 f are read in theranges 32 a, 32 b and 32 c, and the read colors are white (0), blue (1)and black (2), respectively. Also, when the measurement position 36 islocated in the region 47 c of the pattern 46 e, the patterns 46 d, 46 eand 46 g are read in the ranges 32 a, 32 b and 32 c, and the read colorsare white (0), blue (1) and black (2), respectively. Thus, in a statesuch as FIG. 12 in which the pattern 46 c and the pattern 46 d are thesame color and the pattern 46 f and the pattern 46 g are the same colorin particular, the colors read from the respective readers 22 a to 22 cis all the same combination even if the measurement position 36 islocated in which of the region 47 a, 47 b or 47 c. Therefore, it is notpossible to determine that the measurement position 36 is located inwhich of the regions 47 a, 47 b and 47 c, based on only the colors readfrom the three readers 22 a to 22 c. Accordingly, the measurementaccuracy is not necessarily the width P3.

Therefore, the color pattern further is read by using the two additionalreaders 24 a and 24 c, as illustrated in FIG. 12 . In FIG. 12 , therange 34 a corresponding to the reader 24 a is set at a position awayfrom the range 32 a corresponding to the reader 22 a in the +Y directionby the width P1. The range 34 c corresponding to the reader 24 c is setat a position away from the range 32 c corresponding to the reader 22 cin the −Y direction by the width P1. When the range 32 b is located inthe region 47 b of the pattern 46 e as illustrated in FIG. 12 , therange 32 a is located in the region 47 a of the pattern 46 d, the range34 a is located in the region 47 a of the pattern 46 c, the range 32 cis located in the region 47 c of the pattern 46 f, and the range 34 c islocated in the region 47 c of the pattern 46 g. In this case, thepatterns 46 c, 46 d, 46 e, 46 f and 46 g are read in the ranges 34 a, 32a, 32 b, 32 c and 34 b, and the read colors are white (0), white (0),blue (1), black (2) and black (2), respectively.

On the other hand, when the measurement position 36 is located in theregion 47 a of the pattern 46 e, the patterns 46 b, 46 c, 46 e, 46 f and46 g are read in the ranges 34 a, 32 a, 32 b, 32 c and 34 c, and theread colors are blue (1), white (0), blue (1), black (2) and black (2),respectively. When the measurement position 36 is located in the region47 c of the pattern 46 e, the patterns 46 c, 46 d, 46 e, 46 g and 46 hare read in the ranges 34 a, 32 a, 32 b, 32 c and 34 c, and the readcolors are white (0), white (0), blue (1), black (2) and blue (1),respectively. Thus, it is possible to determine that the measurementposition 36 is located in which of the regions 47 a to 47 c by using thereaders 24 a and 24 c disposed at positions shifted from the readers 22a and 22 c by the width P1 in the Y direction. Therefore, even when thetwo patterns 46 with the same color are continuously arranged on theleast significant digit in the Y direction, the measurement accuracy ofthe width P3 can be achieved, Here, in the color pattern of FIG. 5 ,three patterns 46 on the least significant digit with the same color arenot continuously arranged in the Y direction, and it is thereforesufficient that the readers illustrated in FIG. 12 are used.

FIG. 13 is a diagram illustrating a table used in the first embodiment.A color of the range 32 b (i.e., the ternary value), a sum of the valuesof the ranges 30, a combination of the colors of the ranges 34 a, 32 a,32 c and 34 c, and a correction value to be added to the lengthcalculated from the reading result are set in the table as illustratedin FIG. 13 . The sum of the values of the ranges 30 indicates whetherthe sum of the patterns 41 to 45 other than the pattern 46 of the leastsignificant digit is odd or even. The correction value is a value to beadd to the length determined by the colors read in the ranges 30 and 32b. The correction value “−P3” indicates reducing a length correspondingto the width P3 (e.g. 1 mm) from the length determined by the readingresult of the ranges 30 and 32 b. The correction value “+P3” indicatesadding the length corresponding to the width P3 (e.g. 1 mm) to thelength determined by the reading result of the ranges 30 and 32 b.

As described above, the microcomputer 3 determines the length of themeasurement object by using the measurement results of the readers 20,22 a to 22 c, 24 a and 24 c. Therefore, it is possible to improve themeasurement accuracy of the length compared with the width P1 of thepattern, without increasing the number of digits of the color pattern13.

First Variation of First Embodiment

FIG. 14 is a flowchart illustrating a processing executed by themicrocomputer according to a first variation of the first embodiment.The microcomputer 3 determines the colors of the patterns from theoutput of the readers 20 and 22 b (S10). For example, the microcomputer3 executes the operation of S2 to S5 in FIG. 7 to the readers 20 and 22b. In this case, the microcomputer 3 may control the readers 24 a, 22 a,22 c and 24 c so as not to read the color pattern by turning off thereaders 24 a, 22 a, 22 c and 24 c or supplying no power supply to theLEDs 8 and the PTs 9 of the readers 24 a, 22 a, 22 c and 24 c.

Next, the microcomputer 3 extracts readers for reading the pattern fromthe reader 24 a, 22 a, 22 c and 24 c, based on the reading result of thereaders 20 and 22 b (S12). A method of determining the readers to beextracted will be described later. The microcomputer 3 determines thecolors of the patterns read by the extracted readers, based on theoutput from the extracted reader (S14). For example, the microcomputer 3executes the operation of S2 to S5 in FIG. 7 to the extracted readers,and turns off unextracted readers.

Next, the microcomputer 3 determines the length of the measurementobject based on the determined colors of the read patterns (S16). Forexample, the microcomputer 3 executes the operation of S6 and S7 in FIG.7 . Then, the present processing is terminated.

FIG. 15 is a diagram illustrating a table used in the first variation ofthe first embodiment. When the microcomputer 3 determines the color ofthe range 32 b and determines whether the sum of the values of theranges 30 is odd or even, the microcomputer 3 can determine ranges amongthe ranges 34 a, 32 a, 32 c and 34 c required for determining thecorrection value. A reading result in a range enclosed in each of solidlines 50 of FIG. 15 is used for the determination of the length. On theother hand, a reading result in a range enclosed in each of dotted lines52 is not used for the determination of the length. Moreover, either oneof two ranges enclosed in each of dotted lines 54 is used for thedetermination of the length.

When the color of the range 32 b is black (2) and the sum of the valuesof the ranges 30 is odd as illustrated in the first line of FIG. 15 ,the color read in any one of the ranges 34 a or 32 a, and the color readin the range 32 c are used for the determination of the correctionvalue, but the color read in the range 34 c is not used. Therefore, inS12 of FIG. 14 , the microcomputer 3 extracts the reader 22 c and one ofthe readers 24 a or 22 a, and does not extract the reader 24 c and theother of the readers 24 a or 22 a.

When the color of the range 32 b is blue (1) and the sum of the valuesof the ranges 30 is even as illustrated in the fifth line of FIG. 15 ,the color read in ranges 34 a and 34 c are used for the determination ofthe correction value, but the color read in the ranges 32 a and 3 cc arenot used. Therefore, in S12 of FIG. 14 , the microcomputer 3 extractsthe readers 24 a and 24 c, and does not extract the readers 22 a and 22c.

In the first variation, two readers among the four readers 24 a, 22 a,22 c and 24 c are used and the remaining two readers are not used, andit is therefore possible to suppress the consumption of an electricpower.

Second Variation of First Embodiment

A second variation of the first embodiment indicates an example in whichthe accuracy of the length is a half of the width P1. FIG. 16A is anenlarged view of a color pattern according to the second variation ofthe first embodiment. FIG. 16B is an enlarged view of the singlepattern. As illustrated in FIG. 16A, two ranges 32 a and 32 b read bythe readers 22 a and 22 b respectively are provided on the patterns 46of the least significant digit. In the second variation, the pluralityof readers 20 and the reader 22 a are arranged in a row in the Xdirection.

The pattern 46 of the least significant digit is virtually divided intotwo regions 47 a and 47 b in the Y direction, as illustrated in FIG.16B. The width in the Y direction of each of the regions 47 a and 47 bis P5. The width P5 is a half of the width P1. For example, the widthsP1 and P5 are 4 mm and 2 mm, respectively.

In the example of FIG. 16A, the range 32 a is located in the region 47 aof the pattern 46 c, and the range 32 b is located in the region 47 b ofthe pattern 46 d. A distance in the Y direction between the center ofthe ranges 30 and 32 b, and the measurement position 36 as a readingreference is P5/2, for example 1 mm. A distance P6 in the Y directionbetween the centers of the ranges 32 a and 32 b is a sum of the widthsP1 and P5, for example 6 mm. In the example of 16A, the microcomputer 3determines that the measurement position 36 is located in the center ofthe pattern 46 c in the Y direction, from a relationship of the colorread in the range 32 a and the color read in the range 32 b.

FIGS. 17 and 18 are enlarged views of the color pattern according to thesecond variation. In the example of FIG. 17 , the range 32 a is locatedin the region 47 b of the pattern 46 b, and the range 32 b is located inthe region 47 a of the pattern 46 d. In this case, the microcomputer 3determines that the measurement position 36 is located between thepatterns 46 b and 46 c, from the relationship of the color read in therange 32 a and the color read in the range 32 b.

In the states of FIGS. 16A and 17 , the measurement position 36 of FIG.17 is shifted from that of FIG. 16A by the width P5, i.e., 2 mm.Therefore, the microcomputer 3 determines whether the measurementposition 36 is located on which positions of FIGS. 16 and 17_byrelationship between the colors read in the regions 32 a and 32 b, sothat the microcomputer 3 can set the measurement accuracy of the lengthto a half (i.e., 2 mm) of the width P1 (i.e., 4 mm) of the pattern 40.

Moreover, in the example of FIG. 18 , the ranges 34 a and 34 b are addedto the example of FIG. 17 . The range 34 a to be read by the reader 24 ais located away from the range 32 a in the +Y direction by the width P1,and the range 34 b to be read by a reader 24 b is located away from therange 326 in the −Y direction by the width P1. Thereby, even if the twopatterns 46 with the same color, patterns 46 c and 46 d in the exampleof FIG. 18 , are continuous in the Y direction, it is possible todetermine the measurement position 36 and realize the measurementaccuracy of 2 mm.

As described above, in the second variation, it is possible to measurethe length with an accuracy of a half of the width P1 of the pattern.

According to the first embodiment and the first and the secondvariations, the readers 20 (i.e., first readers) optically read thecolors of the ranges 30 (i.e., first ranges) in the patterns 41 to 45(i.e., first patterns) corresponding to the digits except the leastsignificant digit among the plurality of color patterns 40,respectively. The ranges 30 in the plurality of patterns 41 to 45 arearranged in the X direction.

The readers 22 a and 22 c (i.e., second readers) optically read thecolors of the ranges 32 a and 32 c (i.e., second ranges) in the patterns46 (i.e., second patterns) of the least significant digit arranged inthe Y direction among the plurality of color patterns 40, respectively.The ranges 32 a and 32 c are arranged in the Y direction at an intervaldifferent from the width P1 of the pattern 40 in the Y direction.

The microcomputer 3 determines the length of the measurement object withan accuracy smaller than the width P1, from the reading result by thereaders 20 and 22 a and 22 c. The operation of the microcomputer 3 todetermine the length corresponds to an example of a “determiner”. Themeasurement accuracy is a multiple of the number of readers 22 a and 22c. For example, in the first embodiment, the measurement accuracy is ⅓of the width P1 (resolution ⅓), and in the second variation, themeasurement accuracy is ½ of the width P1 (resolution ½). A function ofthe determiner may be realized in cooperation with a processor such asthe microcomputer 3 and software, or may be realized by a dedicatedcircuit.

Thus, it is possible to improve the measurement accuracy of the lengthwithout reducing the width P1 of the color pattern 40 and increasing thenumber of digits.

The ranges 32 a and 32 c are arranged on any of the patterns 46 a to 46g so as to correspond to the regions 47 a to 47 c into which one of thepatterns 46 is virtually divided in the Y direction, respectively.Thereby, the measurement accuracy of the length can be improved by amultiple of the number of regions 47 a to 47 c.

Each of the distance between the ranges 32 a and 32 c and the distancebetween the ranges 32 a and 32 c is larger than the width P1. Thereby,it is possible to widen installation intervals between the readers 22 aand 22 b and between the readers 22 b and 22 c, and there is no need toreduce the sizes of the readers 22 a and 22 c. Also, it is possible tosuppress interference between the ranges 32 a and 32 c.

The readers 24 a and 24 c optically read the colors of the ranges 34 aand 34 c corresponding to the regions 47 a and 47 c other than thecentral region 47 b among the regions 47 a to 47 c, respectively. Aninterval between the range 34 a and the range 32 a corresponding to thesame region 47 a as the range 34 a is the width P1. An interval betweenthe range 34 c and the range 32 c corresponding to the same region 47 cas the range 34 c is the width P1. The microcomputer 3 determines thelength of the measurement object from the reading results by the readers20, 22 a and 22 c, 24 a and 24 c. Thereby, even if the two patterns 46with the same color of the least significant digit are continuous, it ispossible to measure the length accurately.

As described in the first variation, based on the reading results by thereaders 20 and a part of the readers 22 a and 22 c, the microcomputer 3determines whether remaining readers among the readers 22 a and 22 c,and the readers 24 a and 24 c execute the reading. Thereby, it ispossible to suppress the consumption of the electric power of thereaders.

One of the ranges 32 a, 32 b and 32 c is arranged opposite to the ranges30 in the X direction. When the number of regions 47 a to 47 c is odd asin the case of the first embodiment, the range 32 b corresponding to thecentral region 47 b among the regions 47 a to 47 c is arranged oppositeto the ranges 30 in the X direction. Also, when the number of regions 47a and 47 b is even as in the case of the second variation, themeasurement position 36 is shifted from the position of the ranges 30 inthe Y direction by approximately ½ of the width P5.

In the first embodiment and the first and the second variations, thedescription is given of the example that the pattern 46 is virtuallydivided into two or three regions, but the pattern 46 may be dividedinto four or more regions as long as it is divided into a plurality ofregions. Also, the description is given of the case where the colorpattern is the ternary number, but it is sufficient that the colorpattern is N-ary number.

In the first embodiment, an optical reader which is the reader unit 2reads a reading object having the plurality of color patterns, theplurality of color patterns assigned to respective different decimalvalues are arranged in the Y direction, each of the color patterns has aplurality of patterns 40 corresponding to a plurality of digits arrangedin the X direction, and a value of N-ary number is assigned to each ofthe digits. The readers 20 and 22 b are arranged along the X direction,and read patterns 40 corresponding to respective different digits in oneof the color patterns. The readers 22 a and 22 c are arranged oppositeto one of the readers 20 and 22 b along the Y direction, and read thepatterns 40 of the same digit as a digit read by the reader 22 b, thepatterns 40 of the same digit being included in a color pattern adjacentto a color pattern read by the readers 20 and 22 b in the Y direction.Thereby, it is possible to improve the measurement accuracy of thelength.

The second readers includes at least one of the readers 22 a and 22 cthat are arranged at positions away from the reader 22 b by a distancegreater than the width P1, respectively. Thereby, it is possible toimprove the measurement accuracy of the length. The optical readerincludes the readers 24 a and 24 c that are arranged at positions awayfrom the readers 22 a and 22 c by the width P1, respectively. Thereby,it is possible to improve the measurement accuracy of the length.

In the second variation of the first embodiment, the readers 20 and 22 aare arranged along the X direction, and read patterns 40 correspondingto respective different digits in one of the color patterns. The reader22 b is arranged opposite to the reader 22 a along the Y direction, andread the pattern 40 of the same digit as a digit read by the reader 22a, the pattern 40 of the same digit being included in a color patternadjacent to a color pattern read by the reader 22 a in the Y direction.The reader 22 b is arranged at a position away from the reader 22 a by1.5 times of the width P1. Thereby, it is possible to improve themeasurement accuracy of the length.

In the above-described embodiments, the measuring instrument 1 outputsthe decimal value to the external terminal. However, the measuringinstrument may output trinary data, or the actual measured lengthconverted from the read code to the external terminal. When the externalterminal receives the ternary data, the external terminal converts thereceived ternary data into the decimal value and/or into actual measuredlength.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various change, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. An optical reader that reads a reading objecthaving a plurality of color patterns, the plurality of color patternsassigned to respective different values being arranged in a firstdirection, each of the color patterns having a plurality of patternscorresponding to a plurality of digits arranged in a second directionintersecting the first direction, the optical reader comprising: aplurality of first readers that are arranged along the second direction,and read patterns corresponding to respective different digits in one ofthe color patterns; and a plurality of second readers that are arrangedalong the first direction with respect to only a given first reader ofthe first readers, and read patterns of the same digit as a digit readby the one of the first readers, the patterns of the same digit beingincluded in a color pattern adjacent to a color pattern read by thefirst readers in the first direction, wherein a distance along the firstdirection between one of the first readers and one of the second readerswhich are adjacent to each other in the first direction and read thepatterns of the same digit, respectively, is greater than a distancealong the second direction between two of the first readers adjacent toeach other in the second direction, and correction is performed on areading result by the first readers based on a reading result by thesecond readers.
 2. The optical reader as claimed in claim 1, wherein thesecond readers include at least one of readers that are arranged atpositions away from the one of the first readers by a distance greaterthan a width of one of the color patterns in the first direction,respectively.
 3. The optical reader as claimed in claim 2, comprising: athird reader that is arranged at a position away from the at least oneof readers by the width of one of the color patterns in the firstdirection.
 4. An optical reader that reads a reading object having aplurality of color patterns, each of the plurality of color patternsassigned to a respective different value being arranged in a firstdirection, each of the color patterns having a plurality of patternscorresponding to a plurality of digits arranged in a second directionintersecting the first direction, the optical reader comprising: aplurality of first readers that are arranged along the second direction,and read patterns corresponding to respective different digits in one ofthe color patterns; and a second reader that is arranged along the firstdirection with respect to only a given first reader of the firstreaders, and reads a pattern of the same digit as a digit read by theone of the first readers, the pattern of the same digit being includedin a color pattern adjacent to a color pattern read by the first readersin the first direction; wherein the second reader is arranged at aposition away from the one of the first readers by 1.5 times of a widthof one of the color patterns in the first direction, and a distancealong the first direction between one of the first readers and one ofthe second readers which are adjacent to each other in the firstdirection and read the patterns of the same digit, respectively, isgreater than a distance along the second direction between two of thefirst readers adjacent to each other in the second direction, andcorrection is performed on a reading result by the first readers basedon a reading result by the second reader.